The present invention relates to a cushion tire, especially intended for industrial or construction vehicles such as a forklift truck, in which the ride is softened while durability and driving stability are maintained.
In general, heavy duty tires for industrial vehicles such as forklift truck tires require anti-abrasion and anti-cut charcteristics because they are used at comparatively low speed but with heavy load on a road on which nails, stones, wood splinters and the like lie.
Therefore, for such uses there has been used a solid tire of a two-layered construction, in which a tread rubber layer with anti-abrasion and high anti-cut characteristic is used as a radially outer part of the tire to provide a durable treading surface, and a base rubber layer with high modulus of compression elasticity is used as an inner part of the tire to increase the pressure of insertion into the rim, whereby each layer contributes at least partially to the required characteristics.
Recently, in view of the drivers' health care, such tires also require a soft ride, and accordingly, as shown in FIG. 3, there is proposed a solid tire of a triple-layered structure, in which a soft rubber layer C with a high cushion quality is disposed between the base rubber layer A and the tread rubber layer B.
Such triple-layered tire, however, involves the following problems: as an inevitable consequence of the modern tendency of providing low profile tire, the intermediate soft rubber layer C has become thinner thereby reducing its cushion effect. If the soft rubber layer is made thicker, then the volume of the base rubber layer must become smaller thereby decreasing the rigidity thereof. If the pressure of insertion between the tire and the rim is reduced as rim slipping may occur. Also, the soft rubber layer not only improves the ride comfort but also reduces driving stability and durability.
It is therefore, an object of the present invention to provide a cushion tire, which is improved in ride comfort while maintaining anti-abrasion and anti-cut characteristics, driving stability and the pressure of insertion to the rim at the same level as that of former two-layered solid tires.